I had a laptop and he had a smartphone (don't believe it was one of those tablet thingies). What do you mean by client?
The software / website used to perform this transfer.
Although from your previous information someone with a scanner should be able to confirm the first wallet address.
I have Windows 8 now, but the old laptop was Vista, if that's what you're asking. The address was scanned via QR-code either from InstaWallet's page, where it was created, or from blockchain.info, even though there was nothing in it at the time.